Which Files?! Says Poser Core, Legacy, DS Core What do I need for just DAZ?

I dont need Mac and Pc explained, I need PC. But what are Poser Core, Legacy, and DS Core? I know DS is the daz, so I would need DS Core- but what is Legacy? Do I need that? 2.) I don't need Poser Core if I am using Daz, correct? 3. do I need both the trx.zip and the trx. exe?

One other question so this will all be on the same thread- please explain ds.exe and dpc.exe- I think I read at some point that the dpc included poser files, but some products wouldnt work right in daz without them, or something to that effect. The gist was to download both of them. Correct? Is it because some items are in the Poser Library?

I also just encountered meta data that said PS Meta and DS Meta, so that would be poser and Daz- both are exe so again, I would need both?

The dpc files are for Poser, the ds files are for Daz, but sometimes you need both in Daz Studio.

In some cases the ds files act as add-on for the dpc files, it then adds the daz specific settings to the files that come with the dpc.
For example, there would be daz material settings in the ds files, but the geometries and textures are only in the dpc files.
In this case you would need to install both.

In other cases, the ds files will be a complete package.
For example, the geometries and textures are also in the ds files.
In this case you only need to install the ds files.

Now, how can you tell which of the two cases apply to a specific product ?
My rule of thumb is : look at the file sizes. If the ds files are significantly smaller than the dpc files, you would need both. If they are of equal size, you would only need the ds files.

The dpc files are for Poser, the ds files are for Daz, but sometimes you need both in Daz Studio.

In some cases the ds files act as add-on for the dpc files, it then adds the daz specific settings to the files that come with the dpc.
For example, there would be daz material settings in the ds files, but the geometries and textures are only in the dpc files.
In this case you would need to install both.

In other cases, the ds files will be a complete package.
For example, the geometries and textures are also in the ds files.
In this case you only need to install the ds files.

Now, how can you tell which of the two cases apply to a specific product ?
My rule of thumb is : look at the file sizes. If the ds files are significantly smaller than the dpc files, you would need both. If they are of equal size, you would only need the ds files.

The problem is that the site doesn't show the file size and more; so you have to download the files anyway to the size.